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Explicit and Recursive Calculation of Potential and Actual Evapotranspiration
Author(s) -
Lascano Robert J.,
Bavel Cornelius H. M.
Publication year - 2007
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2006.0159
Subject(s) - evapotranspiration , mathematics , humidity , meteorology , environmental science , geography , ecology , biology
The explicit combination method (ECM; Penman, 1948) to calculate potential evapotranspiration (ET p ) is a physically based model using standard climatological data. It is based on an assumption regarding the temperature and humidity at the evaporating surface that is not made in a recursive combination method (RCM; Budyko, 1958). Our objective was to compare the two methods by calculating values of ET p and of actual evapotranspiration (ET a ) using hourly weather data collected on 45 d during the warm season in Lubbock, TX. Results show that on hot summer days ECM underestimated the daily value of ET p and of ET a by as much as 25% compared with RCM. The proposed RCM procedure is based on the same physical principles as ECM, but uses iteration to find an accurate answer. It can easily be used with commercially available mathematical software that has proven to be stable. The RCM needs experimental verification before implementation for crop irrigation.